After the study was published the FDA came out with an alert of a possible relationship between CellCept and a rare, but serious, neurological disease called multifocal leukoencephalopathy (PML). Other diseases associated with CellCept arePolyomavirus associated nephropathy (PVAN), cytomegalovirus (CMV) infections, reactivation of hepatitis B (HBV) or hepatitis C (HCV).